Some services using WebSockets require that the request contains the
Origin header, otherwise these services will return a 403 Forbidden
response. WebSocketServer already supports sending the Origin header,
however LibWeb did not send the origin with the IPC request.
WebSockets got moved from the HTML standard to their own, the new
WebSockets Standard (https://websockets.spec.whatwg.org).
Move the IDL file and implementation into a new WebSockets directory and
C++ namespace accordingly.